The construction of a conventional power conversion device is shown in Patent Document 1, for example. This patent document relates to a so-called 3-level power conversion device, and as shown in FIG. 1, a first switching element, a second switching element and a first coupling diode which constitute a positive side arm are mounted on one surface of a cooling plate, and a third switching element, a fourth switching element and a second coupling diode which constitute a negative side arm are mounted on the opposite surface. For the electrical connection of each switching element, the coupling diode and a capacitor serving as a DC power source, a laminated bus bar obtained by laminating bus bars so that an insulating material is sandwiched therebetween is used, and it is constructed in a U-shape as a whole.
The construction of another conventional power conversion device is shown in FIG. 3 of Patent Document 2. FIG. 3 shows a so-called 2-level power conversion device, and a piece arm is constructed by connecting three switching elements in series. The switching elements of the positive side arm and the negative side arm are disposed so that the connection faces thereof are opposite to each other, and a cooing plate is secured to each switching element. For the electrical connection to the switching element and the DC power source side, a laminated bus bar obtained by laminating bus bars so that an insulating material is sandwiched therebetween is used, and it is constructed in a U-shape as a whole as in the case of the Patent Document 1.
Furthermore, the construction of another conventional power conversion device is shown in FIG. 4 of Patent Document 3. FIG. 4 shows a 2-level power conversion device constructed by a converter and an inverter. One-phase member, that is, a switching element of a positive side arm and a switching element of a negative side arm are mounted on one cooling plate and united, and respective units (respective phases) are stacked so that the cooling plates are parallel to one another.
Patent Document 1: JP-A-10-201249
Patent Document 2: U.S. Pat. No. 5,835,362
Patent Document 3: JP-A-2004-96832